This invention relates to the manufacture of printed circuit boards. More specifically, the invention is concerned with techniques for drilling holes in such circuit boards. It has been proposed to drill holes in a printed circuit board using a laser of suitable power and wavelength. This process is generally referred to as laser ablation. For example, an ultraviolet laser, such as an excimer laser, is suitable for ablating holes through resin-based circuit board substrates. Metal layers on the surface of the board can be used as masks, to define the required pattern of holes.
It has been found that debris from the ablation process (comprising particles of material ejected from the drilled hole) tends to be deposited on the surface of the circuit board, contaminating the board and causing difficulties with subsequent plating steps.
The object of the invention is to provide a way of overcoming this problem.